/Engine/Plugins/Editor/UVEditor/Source/UVEditorTools/Public/Selection/UVToolSelectionAPI.h
Change the transform of the unwrap highlight without rebuilding it (for cheap movement of the highlight when translating the elements). Note that unmoved paired edges (if paired edge highlighting is enabled) will still be rebuilt since their shape may be changed by the movement of adjacent edges.
void SetUnwrapHighlightTransform ( const FTransform & NewTransform )